Shuttle for sewing machines



Nov. 15, 1949 R. cAsAs ROBERT l 2,488,052

SHUTTLE FOR SEWING-MCI'IINS Filed Jem.v 2e, 1945 Patented Nov. 15, 1949 UNI TED STATES.

PATENT OFFICE SHUTTLE FOR SEWING' MACHINES Application-January 26, 1945, Serial No. 574,661

In Switzerland January 27,1944 f 7 Claims.. (Cl. 112--233) Thisinvention is directed to a shuttle for a sewing. .machine provided. with .a device for ten. sioning of the thread enabling the modification ofsthe traction to` beexerted` on the thread during vthe unwinding.

In the known shuttles of this type,v the tension-j ing' deviceV generally comprises an 'adjustable ele-\l ment cooperating with avisual indicator enabling the-marking of its position. The displacement. ofrthis adjustable element eiects through the intermediary of transmission elements, a modication of the pressure of an elastic element acting on the thread in a manner to modify the valueof. .the traction to. be. exerted on it ,during its unwinding.

'.[Theseydevicesv for regulating the pressure of the lelastic element do not always give entire satisfaction because while they do permit modi-` cation in a certainA manner of the pressure of thezelastic element, they ycomprise no .elements permitting the calibration of this pressure. In other words, the scale of the visual indicator cannotygive an indication on the real value ofthe elastic pressure, vb ut gives only points ofv reference. Infact', theelastic` elements of `a given series'havev manufacturing differencesot a kind that a de-l sired pressure is obtained by placing Vthe visual indicator indifferent -positionsiaccording to the characteristics of the elastic element mounted on the shuttle.

The present invention has for its object a shuttle for sewing machines ofthe above mentioned type and which tends tol eliminate the dis-L advantages mentioned, because the tensioning device has an adjustable element provided in the chain of elementsconnecting the adjustable operating element to the elasticelement, the adjusting-element. being disposed in. a manner to permit a correction of thepressure ofV the elastic element for a given position of the indicator and ofi the calibration of this pressure to the desired value. for the zero of the indicator.

The attached: drawings illustrate schematically and-as a matter of example, a form ofk construc-` tion of the object of this'invention.v

Fig. Al is a ,perspective View partly in section;

Fig. 2` is a perspective viewof all the individual parts constituting the regulating device;

Fig. 3 is a plan-view on an increased scale of a `part of the shuttle with the regulating device mounted in, place; Y

Figqi is a plan View of an-alternative form of construction of: one of the parts of the regulating device.`

The shuttle shownis ofthe. rotative type arranged about a horizontal axis, performing twoy revolutions `for each single stitch, It consists chiefly of a movable part of generallycylindrical shape provided 'with a hook |2 and of a part maintained in a stationary position, this part being-composed of rthe following three pieces:V Va cup-shaped piece |3- supporting `a bobbin-reel I4, a ring I5` and a collar |6. These: three pieces are assembled by means. of two screws The movablepart H is provided withv a cylindrical rim I8 and two collar-surfaces i9y and. 2i)Y serving as guiding surfaces for the part maintained in a stationary position. The collar I3 is provided with a cylindrical crown 2| and a flange 22 equipped with a retaining nger 23, this linger being intended to thrust against astop forming parti of a stationary piece of the sewing-machine.`

The regulating device of the tension of the shuttle-thread comprises the following parts:

A rigid pressure-plate` 24 of the same shape as the outer surface of the cylindrical crown 2|. This pressure-platafis, Aprovided with a hole 25, a slot`v26, the twov ends 21- and 28 being bent back in order to become engaged in the two openings, 29 and3|l of the crown 2l.

A pressure spring 3| provided with an opening 32 and having one extremity bent back in such, a. mannerY as; to be held in place by the hole 3D" of the crown 2|.

A lever 33 is provided with a cylindrical hole 34. One end of this lever is curved to forma ngershape cam followerv 35'. The other. end of this 'lever' is -bent downwards as shown at. 36 and engages'with a slot 3l provided in the flangey 22. Because of this bent-down part 36 of the lever, the loop of the needle-thread which ,formsy around the.` shuttle, cannot become hooked toy this lever. Furthermore, the leverv 33 is provided with a tongue 38, which penetrates the openings 25 and 32A and engages with a slot 39 provided in the crown '2 l, thus assuring the respective positions in the-vertical direction of' the three pieces 24, 3| and/33.

An eccentric regulating device 40, formed of a cylindrical body 4|, vhoused in a bore 42 .in the ring |5 and projecting through a corresponding hole 43 provided in the flange 22, carries van eccentric pivot 44 which engages with the hole 34 of the lever 33. This latter turns freely on thev pivot 44. The cylindricalbody 4| is provided with a slot 45 suitable for inserting a screwdriver and for-holding a spring 46, the latter having a U-shape and being made of piano-wire. This spring -is intended for becoming engaged with:

one or the other of a series of slots 41 cut in the wall of the hole 42 and being destined to fix in one or the other position the eccentric regulating device 40.

In assembling the spring 46 in the slot 45 of the cylinder 4| and in the bore 42, the cylinder 4| is first inserted in the bore 42 of the ring l5. The cylinder 4| is then rotated until the slot 45 is aligned with a pair of diametrically disposed grooves 41. While the parts are in this position the spring 46 is inserted in the slot 45 and grooves 41, with its median portion 60 lying in slot 45 and its branches 6| lying in the grooves 41. The branches 6| are so spaced thatthe spring will press slightly in the grooves 41.

A regulating cam 48 is provided which is y formed of an upper plate 49, an intermediate cylindrical part 50 of reduced diameter intended for turning in a hole 5| of reduced diameter provided in the flange 22, and a shoulder 52 which may be introduced through the large opening 53 and which is intended to retain the cam against axial movement in the hole 5|. The upper plate is provided with a screw-driver slot and the shape of its circumference is a curve with increasing diameters. It is provided with marks which may be completed with markingnumbers (viz. Fig. 3). When cam 48 is assembled with the intermediate part 50 in the small hole 5| and the parts 49 and 52 on opposite sides of the ange 22, the pressure of the cam follower on the cam 48 will retain said cam in the small hole 5|.

The Figures 1 and 3 indicate how the diierent elements of the regulating device for regulating the tension of the shuttle-thread are assembled. The lever 33, pivoting around the eccentric pivot 44, bears against the contour of the regulating cam 48 by means of its cam followers 35 and compresses with its other end the pressure spring 3| which in turn acts upon the rigid pressureplate 24.

The shuttle-thread 54, coming oi the bobbinreel |4 and being engaged in the oblique slot 55 cut into the cylindrical crown 2|, glides on the outer wall of this crown, passes into the slot 26 of the pressure-plate 24 and into another slot 56 provided on the upper rim of the crown and is then directed towards the needle-hole of the sewing-machine. In passing over and across the shuttle, the shuttle-thread 54 contributes towards keeping in place the bobbin-reel |4.

The pressure-plate 24 bears against the length of thread between the oblique slot 55 and the slot 26. The tension applied to the shuttlethread results from the friction which it encounters over the distance between the two slots and it is a function of the pressure applied upon plate 24 by the spring 3|. In turn, this pressure is a function of the position which is imposed upon the lever 33 by the regulating cam 48.

When assembling the regulating device, the regulating cam is placed in the 0position, Viz. that the mark 0 is brought face to face with the nger 35. The pressure spring 3|, engaging with one of its ends in the opening 30, acts upon the lever and tends to maintain its finger 35 against the regulating-cam. The regulating cam 48 being placed in an angular position corresponding to zero on its scale, the eccentric 4|) is then angularly displaced until it occupies an angular position at which the lever 33 effects a deformation of the spring 3| just suicient for the free end of the spring 3| to contact with the back of the rigid pressure plate 24 without, however,

exerting a pressure on the latter. For this cam position, the shuttle-thread suffers a minimum of friction over its course through the regulating device and as a result thereof, its tension is very weak. If the cam is turned in a clockwise direction such as to reach successively one of the positions 1, 2 and 3, the lever compresses in an increasing manner the pressure spring 3|, thus compressing more and more the shuttlethread between the pressure-plate 24 and the crown 2|. As a result thereof, the friction to which the thread is submitted over its passage through the pressure device increases also, having as a result that the tension of the shuttlethread becomes a function of the angular position j of the cam 48.

Due to the rigidity of the pressure-plate and due to the fact that it has the same curvature as the outer surface of the crown, the thread is compressed between two surfaces parallel over a certain length. As a result thereof, the friction to which it is submitted for a given position of the cam 48 remains practically constant over a period of time. This arrangement represents therefore a great advantage over the devices known till now and in which the thread is compressed against a rigid surface by means of a spring which bears against it generally on a point only and in which the friction varies greatly over a period of time, these variations being due to the irregular thickness of the thread. The visual indicating device described and which is provided with marks simplies the use of the sewing-machine due to the fact, that it enables the user to set the regulating device to its most favorable position for each kind of thread and for each kind of needle-work and gives the user the possibility to reset this same and most favorable regulation-position each time the same thread for the same needle-work is again used.

The regulating device as well as the visual indicator being located on the upper face of the flange 22, they are accessible from the exterior of the sewing-machine across the opening which permits of placing the bobbin-reel into the shuttle. The regulation of the tension of the shuttle-thread and the control of this tension by means of the marks of the regulating cam constituting the visual indicator are therefore possible without necessitating the dismantling of the shuttle.

In order to avoid the regulating cam 48 from becoming displaced involuntarily by the vibrations of the sewing-machine, the circumference of this cam may be provided with a series of notches 51 engaging with the finger 35 of the regulating lever (Fig. 4).

Finally, the device described has the advantage over all known devices, of enabling a calibration of the pressure of the elastic element and, therefore, an adjustment of the tension to be exerted on the thread during its unwinding.

In fact, in modifying the position of the adjusting eccentric 40, there is the possibility of modifying the pressure of the elastic element for a given position of the adjustable operating cam 48. There is, therefore, the possibility of compensating and eliminating the variation which may exist between two elastic elements of the same series. Thus, there is the possibility of calibrating the tensioning device in the factory in a manner that for all shuttles the unwind'ing of the thread will take place with a given tension exerted on it when the visual indicator is placed in a given position. In thismanner, whatever type of shuttle be used, the operator will always obtain the same tension of the lower thread by the same position of the visual indicator element.A

In the compression-device acting in an elastic manner upon the thread, the rigid pressure-plate may be replaced by an elastic piece. This latter may constitute the spring which determines the elastic tension acting upon the thread.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is:

1. A sewing machine shuttle comprising a casing for receiving a bobbin, and a thread tensioning device on said casing including a spring pressed thread engaging member, two adjusting devices cooperating for varying the pressure exerted by the spring, and visual indicating means associated with one of said adjusting devices.

2. A sewing machine shuttle comprising a casing for receiving a bobbin, and a thread tensioning device on said casing including a spring pressed thread engaging member, two adjusting devices cooperating for varying the pressure exerted by the spring, visual indicating means as sociated with one of said adjusting devices, and resilient retaining means associated with the other adjusting device.

3. A sewing machine shuttle comprising a casing for receiving a bobbin, and a thread tensioning device on said casing including a spring pressed thread engaging member, and means for adjusting the pressure exerted by said spring including a lever having three load bearing points, one of said load bearing points being associated with said spring pressed member, and adjustable Y supports cooperating with the other two of said load bearing points of the lever, one of said adjustable supports having visual indicating means associated therewith.

4. A sewing machine shuttle comprising a casing for receiving a bobbin, and a thread tensioning device on said casing including a spring pressed thread engaging member, and means for adjusting the pressure exerted by said spring including a lever having three load bearing points, one of said load bearing points being associated with said spring pressed member, and adjustable supports cooperating with the other two of said load bearing points of the lever, one of said adjustable supports having visual indicating means associated therewith, said adjustable supports including eccentric cams.

5. A sewing machine shuttle comprising a casing for receiving a bobbin, and a thread tensioning device on said casing including a spring pressed thread engaging member, and means for adjusting the pressure exerted by said spring including a lever having three load bearing points, one of said load bearing points being associated with said spring pressed member, and adjustable supports cooperating with the other two of said load bearing points of the lever, one of said adjustable supports having visual indicating means associated therewith, said adjustable supports including eccentric cams, and the indicating means being formed on the respective cam and having at least one reference mark thereon for indicating the angular position of the cam.

6. A sewing machine shuttle comprising a casing for receiving a bobbin, and a thread tensioning device on said casing including a spring pressed thread engaging member, two adjusting devices cooperating for varying the pressure eX-v erted by the spring, and visual indicating means associated with one of said adjusting devices, said spring pressed thread engaging member including a rigid thread engaging shoe.

'7. In a shuttle for a sewing machine provided with a thread tensioning device comprising a control element with a visual position indicator, a thread engaging member, a lspring for pressing said thread engaging member against a thread, transmission means interposed between said control element and said spring to transmit to said spring variations in the control element to vary the pressure exerted by the spring on the thread engaging member, and means associated with said transmission means to vary the pressure exerted by the spring on the thread engaging member for any given position of said control element.

RAMON CASAS ROBERT.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 58,399 Etzold Oct. 2, 1866 2,181,951 Schenzinger Dec. 5, 1939 

